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<details class="folding-tag" blue><summary> 点击查看使用工具及版本 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center" width=150px>Windows</td>        <td align="left">windows11</td>    </tr>    <tr>        <td align="center">Ubuntu</td>        <td align="left">Ubuntu16.04的64位版本</td>      </tr>    <tr>        <td align="center">VMware® Workstation 16 Pro</td>        <td align="left">16.2.3 build-19376536</td>      </tr>    <tr>        <td align="center">SecureCRT</td>        <td align="left">Version 8.7.2 (x64 build 2214)   -   正式版-2020年5月14日</td>      </tr>    <tr>        <td align="center">开发板</td>        <td align="left">正点原子 i.MX6ULL Linux阿尔法开发板</td>      </tr>    <tr>        <td align="center">uboot</td>        <td align="left">NXP官方提供的uboot，NXP提供的版本为uboot-imx-rel_imx_4.1.15_2.1.0_ga(使用的uboot版本为U-Boot 2016.03)</td>      </tr>    <tr>        <td align="center">linux内核</td>        <td align="left">linux-4.15(NXP官方提供)</td>      </tr>    <tr>        <td align="center">STM32开发板</td>        <td align="left">正点原子战舰V3(STM32F103ZET6)</td>      </tr></table>
              </div>
            </details>

<details class="folding-tag" blue><summary> 点击查看本文参考资料 </summary>
              <div class='content'>
              <table>    <tr><td align="center">参考方向  </td><td align="center">参考原文</td></tr>    <tr><td align="left">---</td><td align="left"><a href="" target="_blank">--- <i class="fa fa-external-link-alt"></i> </a></td></tr></table>
              </div>
            </details>

<details class="folding-tag" blue><summary> 点击查看相关文件下载 </summary>
              <div class='content'>
              <table>    <tr>        <td align="center">---</td>        <td align="left">--- <a href="" target="_blank">  <i class="fa fa-external-link-alt"></i></a></td>      </tr></table>
              </div>
            </details>

<h1 id="一、目录访问"><a href="#一、目录访问" class="headerlink" title="一、目录访问"></a><font size=3>一、目录访问</font></h1><h2 id="1-两个结构体"><a href="#1-两个结构体" class="headerlink" title="1. 两个结构体"></a><font size=3>1. 两个结构体</font></h2><h3 id="1-1-DIR"><a href="#1-1-DIR" class="headerlink" title="1.1 DIR"></a><font size=3>1.1 DIR</font></h3><p>DIR 结构体与 FILE 类似，只是 DIR 存放的是目录相关信息的成员，它的结构，说实话，我只找到了它在 dirent.h 头文件中的声明，详细的结构还是网上搜到的：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> __<span class="title">dirstream</span></span></span><br><span class="line"><span class="class">&#123;</span></span><br><span class="line">    <span class="type">void</span> *__fd;</span><br><span class="line">    <span class="type">char</span> *__data;</span><br><span class="line">    <span class="type">int</span> __entry_data;</span><br><span class="line">    <span class="type">char</span> *__ptr;</span><br><span class="line">    <span class="type">int</span> __entry_ptr;</span><br><span class="line">    <span class="type">size_t</span> __allocation;</span><br><span class="line">    <span class="type">size_t</span> __size;</span><br><span class="line">    __libc_lock_define (, __lock)</span><br><span class="line">&#125;;</span><br><span class="line"><span class="keyword">typedef</span> <span class="class"><span class="keyword">struct</span> __<span class="title">dirstream</span> <span class="title">DIR</span>;</span></span><br></pre></td></tr></table></figure>

<h3 id="1-2-dirent"><a href="#1-2-dirent" class="headerlink" title="1.2 dirent"></a><font size=3>1.2 dirent</font></h3><p>dirent 结构体不仅仅指向目录，还可以指向目录中的具体文件。直接 man 看不到它的定义，使用 man readdir 时可以看到这个结构体定义：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">dirent</span> </span></span><br><span class="line"><span class="class">&#123;</span></span><br><span class="line">    <span class="type">ino_t</span>          d_ino;       <span class="comment">/* Inode number 索引节点号*/</span></span><br><span class="line">    <span class="type">off_t</span>          d_off;       <span class="comment">/* Not an offset; see below */</span></span><br><span class="line">    <span class="type">unsigned</span> <span class="type">short</span> d_reclen;    <span class="comment">/* Length of this record */</span></span><br><span class="line">    <span class="type">unsigned</span> <span class="type">char</span>  d_type;      <span class="comment">/* Type of file; not supported by all filesystem types */</span></span><br><span class="line">    <span class="type">char</span>           d_name[<span class="number">256</span>]; <span class="comment">/* Null-terminated filename 文件名，最长255字符*/</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<h2 id="2-基本函数"><a href="#2-基本函数" class="headerlink" title="2. 基本函数"></a><font size=3>2. 基本函数</font></h2><h3 id="2-1-opendir"><a href="#2-1-opendir" class="headerlink" title="2.1 opendir()"></a><font size=3>2.1 opendir()</font></h3><p>在 linux 下可以使用 man 3 opendir 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line">DIR *<span class="title function_">opendir</span><span class="params">(<span class="type">const</span> <span class="type">char</span> *name)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数打开参数 name  指定的目录, 并返回 DIR* 形态的目录流,。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>name ：需要打开的目录名称（可包括路径名）。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 DIR * 类型，成功时返回目录流指针；出错时返回 NULL 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line">DIR * dp;</span><br><span class="line">dp=opendir(<span class="string">&quot;/home/hk&quot;</span>);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> none </p>
<h3 id="2-2-readdir"><a href="#2-2-readdir" class="headerlink" title="2.2 readdir()"></a><font size=3>2.2 readdir()</font></h3><p>在 linux 下可以使用 man 3 readdir 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="keyword">struct</span> dirent *<span class="title function_">readdir</span><span class="params">(DIR *dirp)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数读取目录流中的内容。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>dirp ：已打开目录的目录流指针变量。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 struct dirent * 类型， struct dirent 是用来描述目录流中一个目录项的结构体类型。成功时返回目录流 dirp 中的下一个目录项（下个目录进入点）；出错或到末尾时返回 NULL 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line">DIR * dp;</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">dirent</span> *<span class="title">dt</span>;</span></span><br><span class="line">dp=opendir(<span class="string">&quot;/home/hk&quot;</span>);</span><br><span class="line">dt = readdir(dp));</span><br><span class="line"><span class="built_in">printf</span>(<span class="string">&quot;%s\n&quot;</span>, dt-&gt;d_name);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> none </p>
<h3 id="2-3-closedir"><a href="#2-3-closedir" class="headerlink" title="2.3 closedir()"></a><font size=3>2.3 closedir()</font></h3><p>在 linux 下可以使用 man 3 closedir 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">closedir</span><span class="params">(DIR *dirp)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数关闭已打开的目录文件。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>dirp ：已打开目录的目录流指针变量。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 int 类型。成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line">closedir(dp);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> none </p>
<h2 id="3-使用实例"><a href="#3-使用实例" class="headerlink" title="3. 使用实例"></a><font size=3>3. 使用实例</font></h2><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><figcaption><span>test.c</span></figcaption><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/** =====================================================</span></span><br><span class="line"><span class="comment"> * Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"> * File name: 01open_close_Dir.c</span></span><br><span class="line"><span class="comment"> * Author   : fanhua</span></span><br><span class="line"><span class="comment"> * Description: 文件IO——目录打开关闭</span></span><br><span class="line"><span class="comment"> * ======================================================</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="comment">/* 头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;dirent.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc,<span class="type">char</span>*argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="comment">/* 定义一个目录结构体指针变量 */</span></span><br><span class="line">	DIR * dp;</span><br><span class="line">	<span class="comment">/* 定义一个目录属性结构体变量 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">dirent</span> *<span class="title">dt</span>;</span></span><br><span class="line">	<span class="comment">/* 1. 打开文件 */</span></span><br><span class="line">	dp=opendir(<span class="string">&quot;/home/hk&quot;</span>);</span><br><span class="line">	<span class="keyword">if</span>(dp &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;opendir&quot;</span>);</span><br><span class="line">		<span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">else</span></span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;opendir&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 2. 打印目录名称 */</span></span><br><span class="line">	<span class="keyword">while</span>((dt = readdir(dp)) != <span class="literal">NULL</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;%s\n&quot;</span>, dt-&gt;d_name);</span><br><span class="line">	&#125;</span><br><span class="line">	closedir(dp);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<p>在终端执行以下命令编译程序：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc test.c -Wall # 生成可执行文件 a.out </span><br><span class="line">./a.out # 执行可执行程序</span><br></pre></td></tr></table></figure>

<h1 id="二、文件访问"><a href="#二、文件访问" class="headerlink" title="二、文件访问"></a><font size=3>二、文件访问</font></h1><h2 id="1-文件权限"><a href="#1-文件权限" class="headerlink" title="1. 文件权限"></a><font size=3>1. 文件权限</font></h2><p>Linux&#x2F;Unix  的文件<strong>调用权限分为三级</strong> : 文件所有者（ Owner ）、用户组（ Group ）、其它用户（ Other Users ）。只有文件所有者和超级用户可以修改文件或目录的权限。</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C/LV04-04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C-%E6%96%87%E4%BB%B6%E5%B1%9E%E6%80%A7%E4%B8%8E%E7%9B%AE%E5%BD%95/img/image-20220511092127123.png" alt="image-20220511092127123" style="zoom: 40%;" />

<table>
    <tr>
        <td align="center" rowspan="2" width=150px>file type</td>
        <td align="center">-</td>
        <td align="left">代表文件</td>
    </tr>
    <tr>
        <td align="center">d</td>
        <td align="left">代表目录</td>
    </tr>
    <tr>
        <td align="center" rowspan="4" width=150px>Owner<br>Group<br>Other Users</td>
        <td align="center">r</td>
        <td align="left">read(可读)</td>
    </tr>
    <tr>
        <td align="center">w</td>
        <td align="left">write(可写)</td>
    </tr>
    <tr>
        <td align="center">x</td>
        <td align="left">execute(可执行)</td>
    </tr>
    <tr>
        <td align="center">-</td>
        <td align="left">无权限</td>
    </tr>
</table>



<p>例如：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C/LV04-04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C-%E6%96%87%E4%BB%B6%E5%B1%9E%E6%80%A7%E4%B8%8E%E7%9B%AE%E5%BD%95/img/image-20220511092326302.png" alt="image-20220511092326302" style="zoom: 50%;" />

<p>对于文件的权限还可以使用三位 8 进制数表示：</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C/LV04-04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C-%E6%96%87%E4%BB%B6%E5%B1%9E%E6%80%A7%E4%B8%8E%E7%9B%AE%E5%BD%95/img/image-20220511092515505.png" alt="image-20220511092515505" style="zoom: 40%;" />

<h2 id="2-基本函数-1"><a href="#2-基本函数-1" class="headerlink" title="2. 基本函数"></a><font size=3>2. 基本函数</font></h2><h3 id="2-1-chmod"><a href="#2-1-chmod" class="headerlink" title="2.1 chmod()"></a><font size=3>2.1 chmod()</font></h3><p>在 linux 下可以使用 man 2 chmod命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">chmod</span><span class="params">(<span class="type">const</span> <span class="type">char</span> *pathname, <span class="type">mode_t</span> mode)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数用于修改文件权限。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>pathname ：需要修改权限的文件的文件名（可以包含路径）。</li>
<li>mode ：要修改的权限（一般为四位十六进制数，后三位代表要修改的权限）。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 int 类型，成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="type">int</span> fd;</span><br><span class="line"><span class="type">char</span> buff[<span class="number">32</span>]=&#123;<span class="number">0</span>&#125;;</span><br><span class="line"><span class="type">int</span> ret;</span><br><span class="line">fd = open(<span class="string">&quot;02read_write.txt&quot;</span>,O_RDWR | O_CREAT | O_APPEND, <span class="number">0666</span>);</span><br><span class="line">ret = read(fd, buff, <span class="number">32</span>);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong></p>
<p>（1）在虚拟机中使用 Linux 时，修改共享文件夹 &#x2F;mnt&#x2F;hgfs&#x2F;file_name 中的文件权限可能会无效，因为这里边的文件同时也是 Windows 下的文件。</p>
<p>（2）可以在终端使用:  ll file_name  命令来单独查看某个文件的权限 。</p>
<h3 id="2-2-fchmod"><a href="#2-2-fchmod" class="headerlink" title="2.2 fchmod()"></a><font size=3>2.2 fchmod()</font></h3><p>在 linux 下可以使用 man 2 fchmod命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">fchmod</span><span class="params">(<span class="type">int</span> fd, <span class="type">mode_t</span> mode)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数修改文件描述符 fd 指向文件的文件权限。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>fd ：文件描述符。</li>
<li>mode ：要修改的权限（一般为四位十六进制数，后三位代表要修改的权限）。</li>
</ul>
<p><strong>【返回值】</strong> 返回值是 int 类型，成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"></span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> none </p>
<h2 id="3-使用实例-1"><a href="#3-使用实例-1" class="headerlink" title="3. 使用实例"></a><font size=3>3. 使用实例</font></h2><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><figcaption><span>test.c</span></figcaption><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/** =====================================================</span></span><br><span class="line"><span class="comment"> * Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"> * File name: 02file_permissions.c</span></span><br><span class="line"><span class="comment"> * Author   : fanhua</span></span><br><span class="line"><span class="comment"> * Description: 文件IO——文件权限修改</span></span><br><span class="line"><span class="comment"> * ======================================================</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="comment">/* 头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="comment">/* chmod 函数 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="type">void</span> <span class="title function_">test_chmod</span><span class="params">()</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc,<span class="type">char</span>*argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	test_chmod();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * @Function: int chmod(const char *path, mode_t mode);</span></span><br><span class="line"><span class="comment"> * @Description: 成功时返回0；出错时返回EOF</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">test_chmod</span><span class="params">()</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="type">int</span> ret;</span><br><span class="line">	ret = chmod(<span class="string">&quot;/home/hk/3Test/test.vim&quot;</span>,<span class="number">0444</span>);</span><br><span class="line">	<span class="keyword">if</span>(ret &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;chmod&quot;</span>);</span><br><span class="line">		<span class="keyword">return</span>;</span><br><span class="line">	&#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<p>在终端执行以下命令编译程序：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc test.c -Wall # 生成可执行文件 a.out </span><br><span class="line">./a.out # 执行可执行程序</span><br></pre></td></tr></table></figure>

<h1 id="三、文件属性"><a href="#三、文件属性" class="headerlink" title="三、文件属性"></a><font size=3>三、文件属性</font></h1><h2 id="1-stat-结构体"><a href="#1-stat-结构体" class="headerlink" title="1. stat 结构体"></a><font size=3>1. stat 结构体</font></h2><p>我们可以在linux内核源码的 include&#x2F;uapi&#x2F;asm-generic&#x2F;stat.h中找到这个结构体。 这个结构体成员是文件的各种信息：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">stat</span> &#123;</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>	st_dev;		<span class="comment">/* Device.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>	st_ino;		<span class="comment">/* File serial number.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>	st_mode;	<span class="comment">/* File mode.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>	st_nlink;	<span class="comment">/* Link count.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>	st_uid;		<span class="comment">/* User ID of the file&#x27;s owner.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>	st_gid;		<span class="comment">/* Group ID of the file&#x27;s group. */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>	st_rdev;	<span class="comment">/* Device number, if device.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>	__pad1;</span><br><span class="line">	<span class="type">long</span>		   st_size;	    <span class="comment">/* Size of file, in bytes.  */</span></span><br><span class="line">	<span class="type">int</span>		       st_blksize;	<span class="comment">/* Optimal block size for I/O.  */</span></span><br><span class="line">	<span class="type">int</span>		       __pad2;</span><br><span class="line">	<span class="type">long</span>		   st_blocks;	<span class="comment">/* Number 512-byte blocks allocated. */</span></span><br><span class="line">	<span class="type">long</span>		   st_atime;	<span class="comment">/* Time of last access.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>  st_atime_nsec;</span><br><span class="line">	<span class="type">long</span>		   st_mtime;	<span class="comment">/* Time of last modification.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>  st_mtime_nsec;</span><br><span class="line">	<span class="type">long</span>		   st_ctime;	<span class="comment">/* Time of last status change.  */</span></span><br><span class="line">	<span class="type">unsigned</span> <span class="type">long</span>  st_ctime_nsec;</span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>   __unused4;</span><br><span class="line">	<span class="type">unsigned</span> <span class="type">int</span>   __unused5;</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>其中主要就是st_mode这个成员，它包含了文件的类型和存取的权限。 st_mode 中有  9 位是代表文件的权限的，我们可以将 1 左移再与 st_mode 做 &amp; 运算，即可判断每位为 1 或者为 0 。</p>
<img data-src="https://fanhua-picture.oss-cn-hangzhou.aliyuncs.com/01%E5%B5%8C%E5%85%A5%E5%BC%8F%E5%BC%80%E5%8F%91/01HQ%E8%AF%BE%E7%A8%8B%E4%BD%93%E7%B3%BB/LV04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C/LV04-04-%E6%96%87%E4%BB%B6%E6%93%8D%E4%BD%9C-%E6%96%87%E4%BB%B6%E5%B1%9E%E6%80%A7%E4%B8%8E%E7%9B%AE%E5%BD%95/img/image-20220511103048184.png" alt="image-20220511103048184" style="zoom:33%;" />

<details class="folding-tag" blue><summary> 点击查看 st_mode 文件权限部分 </summary>
              <div class='content'>
              <table>    <tr><td align="center" width=150px>S_ISUID</td><td align="center">04000</td><td align="left">set-user-ID bit</td></tr>    <tr><td align="center" width=150px>S_ISGID</td><td align="center">02000</td><td align="left">set-group-ID bit</td></tr>    <tr><td align="center" width=150px>S_ISVTX</td><td align="center">01000</td><td align="left">sticky bit</td></tr>    <tr><td align="center" width=150px>S_IRWXU</td><td align="center">00700</td><td align="left">owner has read, write, and execute permission</td></tr>    <tr><td align="center" width=150px>S_IRUSR</td><td align="center">00400</td><td align="left">owner has read permission</td></tr>    <tr><td align="center" width=150px>S_IWUSR</td><td align="center">00200</td><td align="left">owner has write permission</td></tr>    <tr><td align="center" width=150px>S_IXUSR</td><td align="center">00100</td><td align="left">owner has execute permission</td></tr>    <tr><td align="center" width=150px>S_IRWXG</td><td align="center">00070</td><td align="left">group has read, write, and execute permission</td></tr>    <tr><td align="center" width=150px>S_IRGRP</td><td align="center">00040</td><td align="left">group has read permission</td></tr>    <tr><td align="center" width=150px>S_IWGRP</td><td align="center">00020</td><td align="left">group has write permission</td></tr>    <tr><td align="center" width=150px>S_IXGRP</td><td align="center">00010</td><td align="left">group has execute permission</td></tr>    <tr><td align="center" width=150px>S_IRWXO</td><td align="center">00007</td><td align="left">others (not in group) have read,  write,  and execute permission</td></tr>    <tr><td align="center" width=150px>S_IROTH</td><td align="center">00004</td><td align="left">others have read permission</td></tr>    <tr><td align="center" width=150px>S_IWOTH</td><td align="center">00002</td><td align="left">others have write permission</td></tr>    <tr><td align="center" width=150px>S_IXOTH</td><td align="center">00001</td><td align="left">others have execute permission</td></tr></table>
              </div>
            </details>

<p>系统提供了一些宏，可以用这些宏来识别 st_mode 的值，以判定文件的类型和权限。我们可以直接通过宏的返回值判断文件的类型，也可以使用 st_mode &amp; S_IFMT 的值来判断文件类型，例如，</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">stat(pathname, &amp;sb);</span><br><span class="line"><span class="keyword">if</span> ((sb.st_mode &amp; S_IFMT) == S_IFREG) </span><br><span class="line">&#123;</span><br><span class="line">    <span class="comment">/* Handle regular file */</span></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<details class="folding-tag" blue><summary> 点击查看判断 st_mode 文件类型的宏 </summary>
              <div class='content'>
              <table>    <tr><td align="center" width=150px>S_IFMT</td><td align="center">0170000</td><td align="left">文件类型位字段的位掩码</td></tr>    <tr><td align="center" width=150px>S_IFSOCK</td><td align="center">0140000</td><td align="left">S_ISSOCK(st_mode) 是否SOCKET文件,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFLNK </td><td align="center">0120000</td><td align="left">S_ISLNK(st_mode) 是否链接文件,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFREG </td><td align="center">0100000</td><td align="left">S_ISREG(st_mode) 是否常规文件,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFBLK </td><td align="center">0060000</td><td align="left">S_ISBLK(st_mode) 是否块设备,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFDIR </td><td align="center">0040000</td><td align="left">S_ISDIR(st_mode) 是否目录,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFCHR </td><td align="center">0020000</td><td align="left">S_ISCHR(st_mode) 是否字符设备,是返回1,否则返回0</td></tr>    <tr><td align="center" width=150px>S_IFIFO </td><td align="center">0010000</td><td align="left">S_ISFIFO(st_mode) 是否FIFO文件,是返回1,否则返回0</td></tr></table>
              </div>
            </details>

<h2 id="2-基本函数-2"><a href="#2-基本函数-2" class="headerlink" title="2. 基本函数"></a><font size=3>2. 基本函数</font></h2><h3 id="2-1-stat"><a href="#2-1-stat" class="headerlink" title="2.1 stat()"></a><font size=3>2.1 stat()</font></h3><p>在 linux 下可以使用 man 2 stat 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">stat</span><span class="params">(<span class="type">const</span> <span class="type">char</span> *pathname, <span class="keyword">struct</span> stat *statbuf)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数用于获取文件信息。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>pathname ：文件名（可以包含路径）。</li>
<li>statbuf ： struct stat  类型的结构体，用于存放文件属性信息。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 int 类型，成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">stat</span> <span class="title">file_attr</span>;</span></span><br><span class="line"><span class="type">int</span> ret;</span><br><span class="line">ret = stat(<span class="string">&quot;03file_attributes.c&quot;</span>, &amp;file_attr);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> 如果 pathname 是符号链接，那么 stat 获取的是<strong>目标文件</strong>的属性。</p>
<h3 id="2-2-lstat"><a href="#2-2-lstat" class="headerlink" title="2.2 lstat()"></a><font size=3>2.2 lstat()</font></h3><p>在 linux 下可以使用 man 2 lstat 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">lstat</span><span class="params">(<span class="type">const</span> <span class="type">char</span> *pathname, <span class="keyword">struct</span> stat *statbuf)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数用于获取文件信息。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>pathname ：文件名（可以包含路径）。</li>
<li>statbuf ： struct stat  类型的结构体，用于存放文件属性信息。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 int 类型，成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">stat</span> <span class="title">file_attr</span>;</span></span><br><span class="line"><span class="type">int</span> ret;</span><br><span class="line">ret = lstat(<span class="string">&quot;03file_attributes.c&quot;</span>, &amp;file_attr);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> 如果 pathname 是符号链接，那么 lstat 获取的是<strong>链接文件</strong>的属性。</p>
<h3 id="2-3-fstat"><a href="#2-3-fstat" class="headerlink" title="2.3 fstat()"></a><font size=3>2.3 fstat()</font></h3><p>在 linux 下可以使用 man 2 fstat 命令查看该函数的帮助手册。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 函数声明 */</span></span><br><span class="line"><span class="type">int</span> <span class="title function_">fstat</span><span class="params">(<span class="type">int</span> fd, <span class="keyword">struct</span> stat *statbuf)</span>;</span><br></pre></td></tr></table></figure>

<p><strong>【函数说明】</strong>该函数可以由文件描述符取得文件状态。</p>
<p><strong>【函数参数】</strong></p>
<ul>
<li>fd ：已经打开文件的文件描述符。</li>
<li>statbuf ： struct stat  类型的结构体，用于存放文件属性信息。</li>
</ul>
<p><strong>【返回值】</strong>返回值是 int 类型，成功时返回 0 ；出错时返回 EOF 。</p>
<p><strong>【使用格式】</strong>一般情况下基本使用格式如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 需要包含的头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 至少应该有的语句 */</span></span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">stat</span> <span class="title">file_attr</span>;</span></span><br><span class="line"><span class="type">int</span> ret;</span><br><span class="line"><span class="type">int</span> fd;</span><br><span class="line">fd = open( <span class="string">&quot;03file_attributes.c&quot;</span>, O_RDONLY);</span><br><span class="line">ret = fstat(fd, &amp;file_attr);</span><br></pre></td></tr></table></figure>

<p><strong>【注意事项】</strong> none </p>
<h2 id="3-使用实例-2"><a href="#3-使用实例-2" class="headerlink" title="3. 使用实例"></a><font size=3>3. 使用实例</font></h2><details class="folding-tag" blue><summary> 点击查看实例 </summary>
              <div class='content'>
              <figure class="highlight c"><figcaption><span>test.c</span></figcaption><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/** =====================================================</span></span><br><span class="line"><span class="comment"> * Copyright © hk. 2022-2022. All rights reserved.</span></span><br><span class="line"><span class="comment"> * File name: 03file_attributes.c</span></span><br><span class="line"><span class="comment"> * Author   : fanhua</span></span><br><span class="line"><span class="comment"> * Description: 文件IO——文件属性获取</span></span><br><span class="line"><span class="comment"> * ======================================================</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="comment">/* 头文件 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="comment">/* rstat lstat fstat函数函数 */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"><span class="comment">/* time */</span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;time.h&gt;</span></span></span><br><span class="line"><span class="type">void</span> <span class="title function_">test_stat</span><span class="params">()</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc,<span class="type">char</span>*argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">	test_stat();</span><br><span class="line">	<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * @Function: int  stat(const char *path, struct stat *buf);</span></span><br><span class="line"><span class="comment"> *		      int  lstat(const char *path, struct stat *buf);</span></span><br><span class="line"><span class="comment"> * @Description: 如果path是符号链接stat获取的是目标文件的属性；</span></span><br><span class="line"><span class="comment"> *               而lstat获取的是链接文件的属性</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">test_stat</span><span class="params">()</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="comment">/* 定义一个文件属性结构体变量 */</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">stat</span> <span class="title">file_attr</span>;</span></span><br><span class="line">	<span class="type">int</span> ret;</span><br><span class="line">	<span class="type">int</span> i;</span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">tm</span> *<span class="title">t</span>;</span></span><br><span class="line">	<span class="comment">/* 1. 获取文件属性保存到结构体变量中 */</span></span><br><span class="line">	ret = stat(<span class="string">&quot;03file_attributes.c&quot;</span>, &amp;file_attr);</span><br><span class="line">	<span class="comment">/* 2. 判断是否获取成功 */</span></span><br><span class="line">	<span class="keyword">if</span>(ret &lt; <span class="number">0</span>)</span><br><span class="line">	&#123;</span><br><span class="line">		perror(<span class="string">&quot;stat&quot;</span>);</span><br><span class="line">		<span class="keyword">return</span>;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 3. 打印文件存取类型 */</span></span><br><span class="line">	<span class="keyword">if</span>(S_ISREG(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;-&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(S_ISDIR(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;d&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(S_ISCHR(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;c&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(S_ISBLK(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;b&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(S_ISFIFO(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;p&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="keyword">if</span>(S_ISSOCK(file_attr.st_mode))</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="built_in">printf</span>(<span class="string">&quot;s&quot;</span>);</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 4. 打印文件权限 */</span></span><br><span class="line">	<span class="keyword">for</span>(i = <span class="number">8</span>; i &gt;= <span class="number">0</span>; i--)</span><br><span class="line">	&#123;</span><br><span class="line">		<span class="keyword">if</span>(file_attr.st_mode &amp; (<span class="number">1</span> &lt;&lt; i))</span><br><span class="line">		&#123;</span><br><span class="line">			<span class="keyword">switch</span>(i % <span class="number">3</span>)</span><br><span class="line">			&#123;</span><br><span class="line">				<span class="keyword">case</span> <span class="number">0</span>:</span><br><span class="line">					<span class="built_in">printf</span>(<span class="string">&quot;x&quot;</span>);</span><br><span class="line">					<span class="keyword">break</span>;</span><br><span class="line">				<span class="keyword">case</span> <span class="number">1</span>:</span><br><span class="line">					<span class="built_in">printf</span>(<span class="string">&quot;w&quot;</span>);</span><br><span class="line">					<span class="keyword">break</span>;</span><br><span class="line">				<span class="keyword">case</span> <span class="number">2</span>:</span><br><span class="line">					<span class="built_in">printf</span>(<span class="string">&quot;r&quot;</span>);</span><br><span class="line">					<span class="keyword">break</span>;</span><br><span class="line">			&#125;</span><br><span class="line">		&#125;</span><br><span class="line">		<span class="keyword">else</span></span><br><span class="line">		&#123;</span><br><span class="line">			<span class="built_in">printf</span>(<span class="string">&quot;-&quot;</span>);</span><br><span class="line">		&#125;</span><br><span class="line">	&#125;</span><br><span class="line">	<span class="comment">/* 5. 文件字节数(文件大小) */</span></span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot; %d&quot;</span>,(<span class="type">int</span>)file_attr.st_size);</span><br><span class="line">	<span class="comment">/* 6. 打印文件修改时间 */</span></span><br><span class="line">	t = localtime(&amp;file_attr.st_ctime);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot; %d-%d-%d %d:%d&quot;</span>,t-&gt;tm_year+<span class="number">1900</span>,t-&gt;tm_mon+<span class="number">1</span>,t-&gt;tm_mday,t-&gt;tm_hour,t-&gt;tm_min);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot; 03file_attributes.c\n&quot;</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<p>在终端执行以下命令编译程序：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">gcc test.c -Wall # 生成可执行文件 a.out </span><br><span class="line">./a.out # 执行可执行程序</span><br></pre></td></tr></table></figure>

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    <p><span>文章标题:</span><a href="/post/94675df1.html">LV04-04-文件操作-文件属性与目录</a></p>
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